Pawlik, J. (Corresponding author)

1999
Forschungszentrum, Zentralbibliothek Jülich

Report No.: Juel-3643

Abstract: The service life of SOFC (solid oxide fuel cell) systems is an important criterion for their economic viability. The present study addresses the causes of aging of porous nickel-YSZlCe02-cermet electrodes that result in a decrease in the performance of these systems. Electrochemical characterization of the electrodes is achieved by measurement of the currentoverpotential curves and impedance spectra at different temperatures and partial pressures. Overpotential-time curves are recorded under galvanostatic load on the fuel cells at different water partial pressures to determine the influence of the water content in the fuel gas on the aging of the nickel-cermet electrodes. For system simulation, a reaction mechanism is derived from the kinetic characteristics of the hydrogen electrode reaction and converted into a system of differential equations. The measured current-overpotential curves and impedance spectra can be fitted by numerical solution of this system of equations. This fitting of the solution of the system of differential equations to the measured curves of the aged electrodes in conjunction with quantitative microstructural analyses reveals the cause for the aging of the nickel-cermet electrodes.

Keyword(s): electrode ; solid oxide fuel cell ( SOFC ) ; cermet

1. Brennstoffzellen (IEF-3)